By Flip Scipio
The traditional x-braced six-string flattop guitar design has remained in constant use since it was introduced on gut string guitars in the middle of the 19th century. Even though the x-brace pattern was modified circa 1928 to better withstand the increased tension of steel strings, an almost unavoidable feature of most x-braced guitars is that the top gradually changes shape as it slowly folds up under the constant strain of 160 to 180 pounds of string tension.
These powerful forces can raise the strings off the fingerboard to an unacceptable height, necessitating removal of the neck in order to change its pitch angle and thereby lower the action.
This procedure is usually referred to as a neck reset, and it can be quite difficult to perform. Several different tactics are usually used to do this, and the one chosen generally depends on the type or brand of instrument that’s on the operating table. Improper attempts to remove the neck can cause serious damage to the instrument, particularly since the majority of factory guitar necks are attached with a tapered dovetail-type of joint and an adhesive like animal hide glue, polyvinyl acetate, or aliphatic resin glue, all of which produce a tenacious neck-to-body joint.
Since the neck block is usually solid wood, often with the grain running parallel to the grain of the 2mm/.0790” thick sides, it’s easy to crack the neck block and/or the sides while trying to remove the neck as the joint is being heated up.
With guitars that are finished after the neck and body are joined together, like Gibson, Gretsch, Guild, or Lowden acoustics, one starts the process by breaking the finish buildup between the neck and the body. Once the neck is successfully separated from the body, the glue residues have to be removed before the heel area of the neck can be recut to change the neck angle.
This reshaping of the heel is tricky by itself, especially with the elegantly flared CF Martin heel design, the outline of which grows smaller as you pare away a small wedge-shaped area on both sides of the heel.
Performing a proper neck reset on a good quality flattop guitar is decidedly preferable over simply shaving the bridge down to lower the action once the bridge saddle has been lowered to its limit. Removing wood from the bridge can adversely affect the tone, as the bridge is the main transducer that converts a string’s tension into the energy that drives the guitar top.
As a result, an unmolested bridge is a serious, desirable consideration for anyone buying a vintage flattop guitar. The fact that all major manufacturers keep the neck resetting procedure within their limited lifetime warranty policy illustrates that they are aware of the conundrum of responsive soundboard design versus string tension.
There was a time when I was taking many guitars apart simultaneously to do neck resets. This was when I was employed in the repair department at the Guild factory in Westerly, Rhode Island. When it was neck resetting time, I’d usually fill up one of the guitar racks on wheels with neck set candidates and take them apart using two opposing workbenches: one bench had a cradle with a 100-watt infrared light bulb that I’d use to heat up the fingerboard extensions, while on the other bench a large pressure cooker blew steam into the neck joints, which were adhered with hide glue.
Once while my attention was focused on wrestling a neck off an older Guild F50R, I had placed a Guild B30 acoustic bass under the heat lamp without taking into account that the bass guitar body was twice as deep as a regular guitar and therefore much closer to the 100-watt heat source than is advisable. Startled by a warning scream from my superior, I whipped around just in time to see the B30’s celluloid pickguard burst into flames.
As I jumped to the opposing bench and threw the burning bass across the room, the smoke alarm went off. The whole factory had to be evacuated, much to the delight of the factory personnel, who got to enjoy an unexpected break in the springtime sun, peeling their apples and pears while laughing at me, since they all knew where such unrest usually came from.
New York Repairman Flip Scipio still resets necks. Sometimes. Visit flipscipio.com.
A Pain in the Neck—The Difficulties of Neck Replacement
Source: Guitar Aficionado